There have been widely known optical modules each including a housing and an optical element fixed to a bottom plate of the housing. For example, Patent Literature 1 discloses an optical module (referred to as an “optical semiconductor device” in Patent Literature 1) including a housing having a box shape, an optical element fixed to a bottom plate of the housing, and a lid covering opening of the housing and having a window.
Such an optical module state where the optical module, is mounted on various optical Examples of are optical device on which an optical module is mounted include an optical device (referred to as an “optical module” in Patent Literature 9) disclosed in Patent Literature 2. Patent Literature 2 discloses that an optical module (referred to as an “optical element package” in Patent Literature 2) is mounted on the optical device so that an upper surface of the optical module is parallel to a surface of a substrate included in the optical device. As a method of mounting the optical module on the optical device, Patent Literature 2 discloses a method in which the optical module whose upper surface is absorbed by an absorption head is soldered to the substrate in a state where the absorption head is lowered so that legs extending from the absorption head are in contact with the surface of the substrate.